Method, system and apparatus for determining antenna weighting for transmit diversity

Abstract

A method, system and apparatus for determining at least one relative characteristic of a transmit diversity transmitter based on at least one quality indicator based on signals received on the plurality of antennas. In some embodiments of the invention, the relative characteristic may be a relative power or amplitude ratio and/or a phase difference between the signals transmitted on the different antennas.

1. A method of transmitting a signal from a mobile communication device comprising:
 receiving at said mobile communication device a first signal over a plurality of antennas to obtain a respective plurality of receive signals; 
 determining at least one relative quality indicator of said receive signals as received at said mobile communication device; 
 calculating at least one relative transmit characteristic based on said relative quality indicator; and 
 transmitting from said mobile communication device a second signal over said plurality of antennas by applying said at least one relative transmit characteristic to at least one signal path associated with one of said antennas. 
 
     
     
       2. The method of  claim 1 , wherein said relative quality indicator is selected from the group consisting of: a received signal level (Io), a pilot amplitude (EP or ECP), a ratio of a pilot signal amplitude to a noise level (ECP/Nt), a traffic power per bit required (Eb), a traffic power to noise ratio (Eb/Nt), and any combination of thereof. 
     
     
       3. The method of  claim 1 , wherein said at least one relative transmit characteristic comprises a phase difference among respective transmit paths associated with said plurality of antennas. 
     
     
       4. The method of  claim 3 , wherein transmitting said second signal over said plurality of antennas comprises applying said phase difference to at least one signal path associated with one of said antennas. 
     
     
       5. The method of  claim 1 , wherein said at least one relative transmit characteristic comprises a power ratio among respective transmit paths associated with said plurality of antennas. 
     
     
       6. The method of  claim 5 , wherein transmitting said second signal over said plurality of antennas comprises applying said power ratio to at least one signal path associated with one of said antennas. 
     
     
       7. A mobile wireless apparatus comprising:
 a plurality of antennas adapted to receive and transmit signals; and 
 a processor to analyze a relative quality indicator among receive signals received at said plurality of antennas, said relative quality indicator indicative of the quality of the receive signals as received at the mobile communication apparatus, to calculate at least one relative transmit characteristic based on said relative quality indicator, and to apply said at least one relative transmit characteristic to at least one signal path associated with one of said antennas. 
 
     
     
       8. The mobile wireless apparatus of  claim 7 , wherein said relative quality indicator is selected from the group consisting of: a received signal level (Io), a pilot amplitude (EP or ECP), a ratio of a pilot signal amplitude to a noise level (ECP/Nt), a traffic power per bit required (Eb), a traffic power to noise ratio (Eb/Nt), and any combination of thereof. 
     
     
       9. The mobile wireless apparatus of  claim 7 , wherein said at least one relative transmit characteristic comprises a phase difference among respective transmit paths associated with said plurality of antennas. 
     
     
       10. The mobile wireless apparatus of  claim 9 , wherein said processor is to apply said at least one relative transmit characteristic by applying said phase difference to at least one signal path associated with one of said antennas. 
     
     
       11. The mobile wireless apparatus of  claim 7 , wherein said at least one relative transmit characteristic comprises a power ratio among respective transmit paths associated with said plurality of antennas. 
     
     
       12. The mobile wireless apparatus of  claim 11 , wherein said processor is to apply said at least one relative transmit characteristic by applying said phase difference to at least one signal path associated with one of said antennas.